Cables under concrete floor

[sosa]

I've been asked to carry out a domestic job where the only place that i'm going to be able to run cables for the sockets, lights etc. is on a floor which will then be covered in concrete.

Now the most sensible way i can think of doing this is to use steel conduit which will then have the concrete poured onto it, also because the drops to sockets and switches have been specified to be in steel conduit. But my only grievance with using steel conduit is the time its going to take to install it all, so my question to you is there anything more suitable to run the cables in?

I did think about using steel trunking but then thought that this may cause problems with it not being water tight? And so concrete could get into it.

 

[ldoodle]

In my last house the floor was suspended, except for the kitchen extension which was concrete.

What they did was leave a channel un-concreted (for both plumbing and electrical) and use some timber as the walls, then screwed on a timber top. Obviously the walls were left lower than the height of the concrete so the top sat flush.

We bought it in 2005 and it was probably done a few years before that, so not sure if that's the done thing nowadays though.

 

[sosa]

I've just found this http://www.armorductsystems.co.uk/products/floor-trunking/underscreed-trunking-accessories/ so hopefully its going to be a good enough price to go ahead and use.

 

[stillp]

Other sources are available:
http://www.schneider-electric.co.uk...ms/flooring-systems/underscreed-trunking.page

 

[hansPulesh]

My cousin had an extension built a little while ago and I'm not sure if it's the done thing but the builders laid down a set of 4" plastic down pipes into the concrete slab for things like electrics and water pipes.

(By downpipes, I mean the type that are used as WC wate pipes).

They also used these to provide the old air bricks with air from the end of the extension.

I think these are both cheap and easy to use.

Hope that helps.

 

[sparkwright]

No reason PVC circular conduit, 20 or 25 mm can't be used.

Many purpose built flats were done this way in the 70s and 80s.

 

[sosa]

No reason PVC circular conduit, 20 or 25 mm can't be used.

Many purpose built flats were done this way in the 70s and 80s.

I did think about this as well but as the architect has specified steel conduit drops (i.e. the stuff on show) i was a bit hesitant because i couldn't think of a way of joining the plastic onto steel?

 

[sparkwright]

No reason PVC circular conduit, 20 or 25 mm can't be used.

Many purpose built flats were done this way in the 70s and 80s.

I did think about this as well but as the architect has specified steel conduit drops (i.e. the stuff on show) i was a bit hesitant because i couldn't think of a way of joining the plastic onto steel?

Sorry didn't notice the bit about the specification. I suppose it would make sense to do it all in steel conduit then.

Presumably if conduit has been specified, it needs to be constructed so it can be rewired, with singles - so only conduit will do.

I suppose it shouldn't take that long to do the sections in the floor, as appearance isn't too critical, though crossing over will mean more bends.

 

[flyingsparks]

No reason PVC circular conduit, 20 or 25 mm can't be used.

Many purpose built flats were done this way in the 70s and 80s.

I did think about this as well but as the architect has specified steel conduit drops (i.e. the stuff on show) i was a bit hesitant because i couldn't think of a way of joining the plastic onto steel?

Just use female adapters glued onto the ends of the PVC con, or onto boxes, and screw the threaded male galv thread straight into it. Just make sure you earth the galv con at the accessories.